Concerns are increasing for a beluga whale spotted in France's River Seine, far from the cold Arctic waters to which it is more suited, after it refused food and appeared emaciated, a local official said on Saturday.
The beluga is swimming slowly in a basin between two locks about 80 kilometres from Paris. Vets will assess its health before a decision is taken on how to intervene.
Rescuers, who do not know if the four-metre-long mammal is not eating because it lacks energy or is sick, tried feeding it with live trout.
“It didn't seem very interested,” Eure department official Isabelle Dorliat-Pouzet told reporters.
The whale has strayed far from its natural habitat, swimming 160 kilometres up the Seine, past the port of Rouen and towards the French capital.
Markings were beginning to appear on its skin, a possible sign of deteriorating health.
The all-white beluga normally live in Arctic and sub-Arctic oceans, although they are known to sometimes venture into more southern waters and can survive for a short while in fresh water.
In May, an orca separated from its pod died of natural causes in the Seine after attempts to guide it back to sea failed.
A month later, another whale, believed to be a minke, was reported in the Seine.
No decision had been made on how to return the beluga to the ocean, Ms Dorliat-Pouzet said.
One option was to try to lead it to open water. Another was to remove it from the river and transport it, although Ms Dorliat-Pouzet said it was unclear whether the whale was strong enough for such a perilous operation.
Vets will first to attempt to inject it with vitamins.
“Few people think it will return 160 kilometres to the sea on its own,” Ms Dorliat-Pouzet said.